Light absorption by photoplankton and the vertical light attenuation: ecological and physiological significance

F. Schanz, P. Senn, Z. Dubinsky

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

22 Scopus citations


The chlorophyll a specific light attenuation coefficient kc, (in m2mg-1 chl a), is an apparent optical property of the underwater light field, resulting from the interaction between sunlight and the phytoplankton suspended in natural waters. The determination of kc is carried out under the natural light conditions of a water body, whereas the specific light absorption coefficient of chlorophyll a, aph (in m2mg-1 chl a), is an inherent optical property of the phytoplankton. That parameter, aph, is determined using a laboratory spectrophotometer. Both kc and aph are necessary to calculate the quantum requirement of phytoplankton photosynthesis from α, the linear part of the photosynthesis versus irradiation curve. The spectral distribution of kc(λ) and aph(λ) contains information about the species composition of the phytoplankton community. Different ways to determine kc or aph are presented. It is relatively easy to evaluate k-c(= k-c(PAR)), the wavelength-average over the photosynthetically available radiation (PAR) range, assumed to be from 400 nm to 700 nm. Alternatively, in the literature such values were also calculated from the much more difficult to measure kc(λ)-spectrum, and the spectral distribution of underwater irradiance, E(λ). The values of kc and aph are influenced by technical, physical and biological factors: the method of chlorophyll determination, the filter loading, the light properties of the water bodies, the species composition of the phytoplankton community, including cell geometry and size, the ultrastructure of chloroplasts and the physiological status of the cells, resulting from senescence, nutrient limitation or photoacclimation.

Original languageEnglish
Title of host publicationOceanography and Marine Biology
Subtitle of host publicationan annual review. Vol 35
EditorsA.D. Ansell, R.N. Gibson, M. Barnes
PublisherUCL Press
Number of pages25
StatePublished - 1997
Externally publishedYes

Publication series

NameOceanography and Marine Biology: an annual review. Vol 35
ISSN (Print)0078-3218


Dive into the research topics of 'Light absorption by photoplankton and the vertical light attenuation: ecological and physiological significance'. Together they form a unique fingerprint.

Cite this